Study: Many U.S. cities unprepared for future heat waves
Cities tend to run much hotter than nearby rural areas. This is due to what’s known as the urban heat island effect. There are fewer trees and plants in the city to enable evaporation. Buildings and pavements absorb more warmth from the sun. And factories and automobiles give off waste heat. That all adds up. On a hot summer afternoon, a large city can easily run 5°F to 18°F hotter than surrounding rural areas, enough to turn an unpleasant heat wave into a deadly calamity.